I've never had to, nor have I seen anyone that has. Well, maybe if you're quadrupiling a quantity. (example, 2/3 cup of butter x4), but for most people, I haven't seen a need for it.
" ... multiply by the RECIPROCAL of the divisor.
multiply and divide fractions!-.-
We multiply fractions in real life when we need to find a part of a part. For example, if a recipe requires ( \frac{2}{3} ) of a cup of sugar and you want to make only ( \frac{1}{2} ) of the recipe, you would multiply ( \frac{2}{3} ) by ( \frac{1}{2} ) to determine the amount of sugar needed. Another example is when calculating discounts, where you might find a fraction of a fraction to determine the final price of an item.
When we simplify fractions.
No, you cannot use models to multiply fractions!!
You use fractions for LOTS of things in the real world like money, gambling, shopping, clothing, etc.
when simplifying fractions
in cookbooks and recipes
In calculating fractions.
You multiply the fractions
When you add or subtract fractions you cross multiply and when you multiply or divide fractions you across multiply.
Yes you do.